Length: 4.5 - 6.5 mm
The hind legs of Laccophilus species are flattened like paddles and have stiff hairs that increase the surface area for better propulsion. Unlike some of the other aquatic beetles, members of the family Dytiscidae move their back legs in unison to swim, rather than alternating left and right.
Laccophilus maculosus is widespread across Canada and the United States.
Left: Though the markings are somewhat different on this second beetle, it too appears to be the same species (L. maculosus) as the beetle shown at the top of the page. Both were photographed in coal mine settlement ponds in Upshur County, West Virginia.
American Insects site